Document FR 2 691 520 describes a sealed and thermally insulating tank successively having, in the direction of the thickness, from the inner side to the outer side of the tank, a primary sealing membrane, in contact with the fluid contained in the tank, a primary thermal insulation barrier, a secondary sealing membrane, a secondary thermal insulation barrier and a carrier structure which is constituted by metal sheets which form the hull or the double hull of a merchant tanker, such as a methane tanker.
The corner zones of the tank are produced from preassembled corner structures, in the form of a dihedron, which are illustrated in FIG. 3 of the document FR 2 691 520. Such a preassembled corner structure comprises two beveled insulating plates which form the secondary thermal insulation barrier, a flexible membrane resting on the insulating plates of the secondary thermal insulation barrier and constituting the secondary sealing barrier, a plurality of insulating blocks of the primary thermal insulation barrier which are adhesively bonded to the secondary sealing membrane and metal corners of a primary sealing membrane which are fixed to the insulating blocks of the primary thermal insulation barrier.
The adhesive bonding of the insulating blocks of the primary thermal insulation barrier to the secondary sealing barrier is not completely satisfactory. In particular, the bonding operations of the insulating blocks are complex to carry out.
Given this complexity, the adhesive bonding of the insulating blocks of the primary thermal insulation barrier to the secondary sealing membrane is brought about in the workshop and the corner structures are integrally preassembled. However, such preassembled corner structures are heavy, making the transport and handling thereof to and at the installation site of the tank difficult.